package com.java110.utils.id;
/**
 * 1 41位的时间序列（精确到毫秒，41位的长度可以使用69年）
 * 2 10位的机器标识（10位的长度最多支持部署1024个节点） 
 * 3 12位的计数顺序号（12位的计数顺序号支持每个节点每毫秒产生4096个ID序号） 最高位是符号位，始终为0。
 *
 * ---------------------
 *
 * 本文来自 xxj_jing 的CSDN 博客 ，全文地址请点击：https://blog.csdn.net/xxj_jing/article/details/72844821?utm_source=copy
 */
public class GeneratorUnionID {

    private final long workerId;

    private final static long twepoch = 1288834974657L;

    private long sequence = 0L;

    private final static long workerIdBits = 4L;

    public final static long maxWorkerId = -1L ^ -1L << workerIdBits;

    private final static long sequenceBits = 10L;

    private final static long workerIdShift = sequenceBits;

    private final static long timestampLeftShift = sequenceBits + workerIdBits;

    public final static long sequenceMask = -1L ^ -1L << sequenceBits;

    private long lastTimestamp = -1L;

    public GeneratorUnionID(final long workerId) {
        if (workerId > this.maxWorkerId || workerId < 0) {
            throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", this.maxWorkerId));
        }
        this.workerId = workerId;
    }

    public synchronized long nextId() {
        long timestamp = this.timeGen();
        if (this.lastTimestamp == timestamp) {
            this.sequence = (this.sequence + 1) & this.sequenceMask;
            if (this.sequence == 0) {
                System.out.println("###########" + sequenceMask);
                timestamp = this.tilNextMillis(this.lastTimestamp);
            }
        } else {
            this.sequence = 0;
        }
        if (timestamp < this.lastTimestamp) {
            try {
                throw new Exception(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", this.lastTimestamp - timestamp));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        this.lastTimestamp = timestamp;
        long nextId = ((timestamp - twepoch << timestampLeftShift))
                | (this.workerId << this.workerIdShift) | (this.sequence);
        System.out.println("timestamp:" + timestamp + ",timestampLeftShift:" + timestampLeftShift + ",nextId:" + nextId + ",workerId:" + workerId + ",sequence:" + sequence);
        return nextId;
    }

    private long tilNextMillis(final long lastTimestamp) {
        long timestamp = this.timeGen();
        while (timestamp <= lastTimestamp) {
            timestamp = this.timeGen();
        }
        return timestamp;
    }

    private long timeGen() {
        return System.currentTimeMillis();
    }

    public static String valueOfString(){
        GeneratorUnionID worker = new GeneratorUnionID(1);
        return String.valueOf(worker.nextId());
    }

//    public static void main(String[] args) {
//        GeneratorUnionID worker2 = new GeneratorUnionID(2);
//        System.out.println(worker2.nextId());
//    }
}

